Gaging tapered bores



Patented Mar. 18, 1958 GAGING TAPERED BORES William D. Schmidt and Alfred Voedisch, Holden, Mass., assignors, by mesne assignments, to Heald Machine Company, a corporation of Delaware Application March 25, 1955, Serial No. 496,730

2 Claims. (Cl. 73-373) This invention relates to gaging tapered bores and more particularly to apparatus whereby a pneumatic signal indicative of the size and taper of a conical bore may be obtained.

In the machining of tapered bores, and particularly in the finishing of such bores by the use of internal grinding apparatus, there exist many problems of control. Not only is it desirable to measure and control the mean diameter of the bore, but the amount of the taper is quite important. It has been desired for some time to use the method of internal grinding often resorted to in the finishing of cylindrical bores, i. e., by reciprocating a small revolving cylindrical grinding wheel in and out of one end of the bore, while causing a pneumatic gage to partake of the same motion, whereby the gage occupies the bore for making measurements when the wheel is absent. However, the prior art apparatus has not been capable of such operation. These, and other limitations in the prior art apparatus, are obviated by the present invention in a novel manner.

It is, therefore, an outstanding object of the present invention to provide a means for gaging the diameter and taper of internal conical surfaces.

Another object of this invention is the provision of a pneumatic gage for use with a tapered bore.

It is -a still further object of the instant invention to provide means applicable to the small end of a frustoconical bore for giving a pneumatic signal indicative of the diameter and taper thereof.

Another object of the invention is the provision of a gage for tapered bores which is simple in construction, easy to manufacture, and low in cost and which may be used with an internal grinder having pneumatic controls with a minimum of modification of the said grinder.

With these and other objects in view, as will be apparent to those skilled in the art, the invention resides in the combination 'of parts set forth in the specification and covered by the claims appended hereto.

The character of the invention, however, may be best understood by reference to certain of its structural forms, as illustrated by the accompanying drawings in which:

Figure 1 is an enlarged view, partially in section, of a preferred embodiment of the invention, and

Figure 2 is a sectional, somewhat schematic view modification of the invention.

Referring to the drawing, the gage, indicated generally by the reference numeral 10, is shown in use with an article having tapered bore such as the roller bearing race 11 having a 'frusto-conical bore 12. A small cylindrical grinding wheel 13 is shown in an intermediate position of its cycle of reciprocation. The gage comprises an actuating shaft 14 and a main gage body 15. The actuating shaft 14- is generally cylindrical and terminates at the gaging end in a reduced cylindrical portion 16 with a fit for slight sliding motion in a cylindrical bore 17 in the main gage body. A radial shoulder 18 joins the two cylindrical surfaces of the actuating member. The outward end of the reduced portion 16 is provided with a ofa threaded axial recess in which is normally threaded a cap screw 20 having a wide head for retaining the main gage body on the actuating shaft. A radial passage 21 enters the surface of the reduced portion intermediate of its ends and meets an axial passage 22 which extends along the actuating member away from the gaging end for a purpose to be explained more fully hereinafter.

The main gage body 15 is provided with a cylindrical surface 23 extending from one end thereof, and terminating in a shoulder or radial surface 24 comprising one surface of a radial flange 25 extending outwardly of the surface 23 a considerable distance. The other side of the flange 25 is provided with a radial surface 26 which extends inwardly to a short cylindrical surface 27.- A re-' silient member such as a rubber O-ring 28 fits closely around the surface 27 and is pressed between the radial surface 18 of the actuating member and the radial surface 26 of the main gage body. The end of the bore 17 adjacent the cap screw 20 is provided with a counterbore 29 in which resides a sealing means such as a rubber O-ring 30 which fits tightly between the surface of the reduced portion 16 and the cylindrical surface of the counterbore 29. A shallow counterbore 31 is provided in the bore 17 intermediate of its ends; this counterbore extends axially a sufiicient distance so that the passage 21 opens well within it. From the counterbore 31 extend a number of relatively small passages 32, these passages opening on the cylindrical surface 23 intermediate of its ends.

The operation of the invention will be clearly understood in view of the above description. The gage 10 is used in a machine of the type shown and described in the co-pending patent application of William D. Schmidt et al., Serial Number 415,048, filed March 9, 1954, entitled Internal Grinding Machine, now Patent No. 2,771,714, issued November 26, 1956. More specifically, the passage 22 is connected to the pneumatic controls of the machine, which controls cause the machine to carry out a predetermined cycle of operation and which also maintains a constant air pressure at the gage even when the gage does not reside within the workpiece. The workpiece 11 is held by the usual means in the machine and is subjected, as is customary, to a rotative movement about its axis. Since the gage 10 is connected to the machine in a position usually reserved for conventional pneumatic gages, it is subjected to a reciprocatory motion in and out of the workpiece; this motion is similar to the reciprocatory motion to which the wheel 13 is subjected, the gage residing within the bore 12 of the workpiece when the wheel is withdrawn therefrom, and vice versa. The wheel 13 is, 'of course, rotated about its axis at a high rate of speed. In practice, the workpiece 11 is mounted with the smaller end of the tapered bore 12 adjacent the gage. As the wheel 13 is withdrawn from the larger end of the bore, the gage 10 enters the bore from the other end. The gage continues to move I into the bore until the radial surface 24 of the main gage body 15 strikes the radial surface surrounding the entrance to the smaller end 'of the workpiece. The mechanism of the machine which moves the actuating shaft 14 is of a non-positive type and permits the gage to" stop when the surface 24 of the flange 25 strikes the workpiece. Furthermore, the shock of the sudden engagement of these surfaces is absorbed by the rubber O-ring 28 as the main gage body is caused to slide slightly along the reduced portion 16 of the actuating shaft.

Air then flows through the passage 22 and the passage 21 into the counterbore 31 from whence it progresses into the small passage 32. The air flows from the passages 32 into the wedge-shaped space between the conical surface of the bore 12 and the cylindrical surface 23 of the main gage body and from there into the room.

essence Although all other passages of the system remain of constant size, the said wedge-shaped space will vary in the manner in :whichtit aestri'cts the how of air. The restriction will vary with both the average diameter of the bore and :the :slope .or cone angle of the surface. For instance, it aisrevident'that an increase in the average diameter ,of the bore "will cause 'agreater separation between ithe cylindrical surface 23 and the surface of the bore, thus :causing a greater flow of air. In the same manner, :anincreaseiin the cone angle or taper will resultlin-a greater show of air :because of the fact that the averagecross-section.ofthe gap between the bore surface and the.,gage .surfacewill be increased. The changes in air flow from Ithe gage will :be felt in the pneumatic controls o'f the machine and ,proper action will be taken by the controls based on the information thus obtained. Escape of air tthrough the space between the reduced portion :16 ofthe actuating shaft and the bore 17 of the main iga'ge body isprevented by the sealing effect of the rubber Daring :30.

It .is evident thatthe best results will be obtained when the :diameter ofthe cylindrical surface 23 is very close to V the minimum diameter of the unfinished tapered bore.

IZhus,-tl:1e;gage will be able to enter the small end of the bore and yet the gap between the cylindrical surface andithe :bore surface will be at a minimum value. Furthermore, it is well to locate the passages 32 fairly close to :thexradial surface :24 for the same reason; this would depend, of course, to a .great extent on the degree of taper. .If the taper is very small, the passages may be located a considerable distance from the shoulder with out excessive air flow.

.In Figure v2 is shown a :modification of the invention that is particularly useful in measuring the taper of a bore. The gage Ilfllis shown as comprising a main gage body 115 and an actuating shaft 114. The gage is shown inoperative relation .to 'aworkpiece 111 having a tapered bore 112. The :main gage body has a cylindrical surface 123 and :a radial shoulder surface 124. The actuating shaft :is provided with a reduced portion 116 with a fit for slight sliding motion within a bore 117 in the main gage body. A rubber o-ring 128 is located between radial surfaces of the shaft and body. Two counterbores 131 and 131a are provided in the bore 117 of the body and .from these counterbores extend two groups 132 and 132a, :respectively, "of relatively 'small passages. These passages are spaced a substantial distance apart along the surface .123. Extending through the actuating shaft and emerging on the reduced portion within the area subtended by the counterbores 131 and 131a are passages 122 and 122a, respectively. The operation of this embodiment of the invention is very similar to that described Iabove in connection with Figure 1. However, in this case "the flow of air through the group 132 of passages "is measured separately from the flow of air through the group 132a; these readings are compared in the pneumatic controls of the machine and, since the difference is indicative of the amount of taper, the difference may be used to control the machine and make adjustments.

While it will be apparent that the illustrated embodiment of the invention herein disclosed is well calculated to adequately fulfill the objects and advantages primarily stated, it is to be understood that the invention is suscepti- 'ble to variation, modification and change'within'tl'ie spirit and scope of the subjoined claims.

The invention having been thus described, what is claimed as new and desired to secure by Letters Patent l. A gage for use with an internal grinding machine for finishing a workpiece having a tapered bore comprising a main gage body adapted to be moved in and out of the small end 'of the bore. the body having a cylindrical surface extending to the end which enters the bore first, the said cylindrical surface terminating in a flange having a radial surface adapted to strike the surface of the workpiece around the entrance to the bore and an opposite radial surface, there being air passages opening on the said cylindrical surface at a portion thereof removed from the said radial surface, an actuating shaft having a'reduced portion -on which the main gage body is *slidably mounted, the shaft having a radial sun fa'ceextending between the reduced portion and the remainder of the shaft and a resilient member interposed between :said radial surface of the shaft and the said -o'p p'osi'te radial surface of the body to absorb the shock-of the radial surface striking the workpiece and to resist axial sliding movement.

2. Agage for use with an internal grinding machine for finishing a workpiece having a tapered bore co'rnpfising a main zgage body adapted to be moved in and out of the small end of the bore, the body having a cylindrical surface extending to the end which enters the bore first, the said cylindrical surface terminating in a flange having a first radial surface adapted to strike the surface of the workpiece around the entrance to the bore and a second radial surface on the opposite side of the flange, and there being air .passages opening on the said cylindrical surface at a portion thereof removed from the said radial surface, an actuating shaft having a cylindrical reduced end portion, there being a radial surface extending between the reduced end portion and the remainder of the shaft, the main gage 'body having a bore, the reduced portion of the shaft lying within the bore, the body being capable of slight sliding motion therealong, and an O-ring of rubberlike material interposed between said first r'adial surface of'the body and the said radial surface 'of the shaft to restrict resiliently the said motion, to absorb the shock of the said radial surface striking the surface of the workpiece, and to maintain the radial surface in contact with the workpiece so that the passages will reside a predetermined distance within the bore.

References Cited in the file of this patent UNITED STATES PATENTS 2,358,769 Aller Sept. 19, 1944 2,360,705 Moore on. 17, 1944 2,514,956 Kuebler g July 11, 1950 2,580,412 Darmu'cl Ian :1, [9 52 2,718,140 Alle'r Sept. 20, 1955 2,732,711 Dai'fnody Jan. 31, 19 56 FOREIGN PATENTS 658,754 Great Britain Oct. 1( i 827,258 Germany Ian. 10, 1932 

